CZ:Ref:DOI:10.1007/s00439-006-0279-x

Souter, V.; M. Parisi & D. Nyholt et al. (2007), "A case of true hermaphroditism reveals an unusual mechanism of twinning", Human Genetics 121 (2): 179–185, DOI:10.1007/s00439-006-0279-x ^[e]

Quotes from abstract: "Traditionally twins are classified as dizygous or fraternal and monozygous or identical ... We report a rare case of 46,XX/46,XY twins: Twin A presented with ambiguous genitalia and Twin B was a phenotypically normal male. These twins demonstrate a third, previously unreported mechanism for twinning. ... Most significantly the twins shared 100% of maternal alleles and approximately 50% of paternal alleles in DNA analysis of skin fibroblasts. The twins are chimeric and share a single genetic contribution from their mother but have two genetic contributions from their father thus supporting the existence of a third, previously unreported type of twinning."